1. Field of the Invention
The present invention relates to an electric outboard motor.
2. Description of the Related Art
In recent years, in consideration of an influence on an environment, an electric outboard motor to be driven by an electric motor has been attracting attention. For example, in Patent Document 1 and Patent Document 2, there has been disclosed an electric outboard motor having an electric motor housed in a motor room of an outboard motor main body. These electric outboard motors each have a structure such that output of the electric motor, namely rotation of an output shaft is transmitted to a propeller shaft through a drive shaft and a bevel gear to rotate a propeller. Further, in these electric outboard motors, the motor room covered with a motor cover is formed in order to house the electric motor therein. In the above motor room, besides the electric motor, a rechargeable battery supplying power to the above electric motor and a control unit controlling rotation speed of the electric motor and the like are provided. According to the electric outboard motors as above, as compared with an engine outboard motor, for example, an exhaust gas is not discharged into the water, so that it is possible to reduce the influence on the environment.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2005-153727    [Patent Document 2] Japanese Laid-open Patent Publication No. 2005-162055
However, in the above-described electric outboard motors, all the electric motor, the rechargeable battery, and the control unit are large and heavy objects. Thus, when they are provided in the electric outboard motor, a problem that the electric outboard motor is increased in size and weight is caused. The weight of the electric outboard motor changes depending on a cruising distance and a cruising time, but it becomes heavy as compared with, for example, an engine outboard motor with the same output and the same cruising distance.
Further, an outboard motor is normally attached to overhang from a stern (transom board) of a hull to the outside. Thus, in the case when the electric outboard motor is used, not only the total weight of a hull is simply increased but also a barycenter of the hull is positioned at the rear. As a result, a bow of the hull rises during traveling to thereby affect the front view of a boat operator. In the above case, it is possible to consider that the boat operator moves to the front of the hull to maintain a weight balance of the hull, but the boat operator is away from the outboard motor to cause a fear that it becomes difficult for the boat operator to manipulate the electric outboard motor.
Further, when the weight of the electric outboard motor is increased, a tilt-up manipulation, which is performed when the electric outboard motor is brought up from the water, is not easily performed and portability of which the electric outboard motor is detached from the hull to be carried to a storage place is also reduced. Further, inertial mass at the time of traveling also increases, and thus when an underwater obstacle and the electric outboard motor collide at the time of traveling, a tilt-up operation for reducing impact weighting is not easily performed to cause a fear that impact weighting against the electric outboard motor increases. Further, the electric outboard motor is increased in size, and thus when the electric outboard motor is tilt-up manipulated, an overhang of the electric outboard motor toward the hull is increased to cause a fear that the overhang interferes with the hull or an occupied space of the electric outboard motor in the hull is increased.